In recent years, the features of modern, ultra-high density integrated circuits have steadily decreased in size in an effort to enhance overall speed, performance, and functionality of circuits. As a result, the semiconductor industry continues to experience tremendous growth due to significant and ongoing improvements in integration density of a variety of electronic components, such as transistors, capacitors, diodes, and the like. These improvements have primarily come about due to a persistent and successful effort to reduce the critical dimension (i.e., minimum feature size) of components, directly resulting in the ability of process designers to integrate more and more components into a given area of a semiconductor chip.
Improvements in integrated circuit design have been essentially two-dimensional (2D); that is, improvements have been related primarily to the layout of the circuit on the surface of a semiconductor chip. However, as device features are continuing to be aggressively scaled, and more semiconductor components are being placed onto the surface of a single chip, the required number of electrical interconnects necessary for circuit functionality dramatically increases, resulting in an overall circuit layout that is increasingly becoming more complex and densely packed. Furthermore, even though improvements in photolithography processes have yielded significant increases in integration densities of 2D circuit designs, simple reduction in feature size is rapidly approaching limits of what can presently be achieved in only two dimensions.
As the number of electronic devices on single chips rapidly increases, three-dimensional (3-D) integrated circuit layouts, such as stacked chip designs, are being considered for certain semiconductor devices or circuits, in part to overcome the feature size and density limitations associated with 2-D layouts. In one three-dimensional integrated design, two or more semiconductor dies may be bonded together, and electrical connections formed between the dies.
Circuit elements, such as capacitors, inductors, transformers, etc., are widely used in various electronic circuits. Typically, an inductor or transformer is a discrete device, separately manufactured and integrated into an electronic circuit via coupling to, for instance, a motherboard of the electronic circuit. Existing designs of such circuit elements may not lend themselves to easy integration into three-dimensional circuit layouts.